Chapter 24

Studies have shown that reindeer and musk-ox, two Arctic mammals (see Chapter 11), have evolved hemoglobins that are unustally low in their sersitivity to temperature cocrpared with the hemoglobins of moet large mammals. The researchers who made this discuvery hypothesized that a particularly low thermal sensitivity is required for hemsoglobin to unload ${\mathrm{O}}_2$ to an adequate extent in the distal parts of these animals' legs, where tissue temperatures may be ${25}^{\circ }\mathrm{C}$ cooler than in the thorax (see Figure 10.32). Explain the rationale for this hypothesis. In answering discuss how the temperature of the hemoglobin molecules changes as blood flows between the lungs and the legs in cold weather. If possible, design studies to test the hypothesis.

Studies have shown that reindeer and musk-ox, two Arctic mammals (see Chapter 11), have evolved hemoglobins that are unustally low in their sersitivity to temperature cocrpared with the hemoglobins of moet large mammals. The researchers who made this discuvery hypothesized that a particularly low thermal sensitivity is required for hemsoglobin to unload ${\mathrm{O}}_2$ to an adequate extent in the distal parts of these animals' legs, where tissue temperatures may be ${25}^{\circ }\mathrm{C}$ cooler than in the thorax (see Figure 10.32). Explain the rationale for this hypothesis. In answering discuss how the temperature of the hemoglobin molecules changes as blood flows between the lungs and the legs in cold weather. If possible, design studies to test the hypothesis.